Add MP4 extraction of Dolby TrueHD samples

Extract 16 access units per readSample call to align
with what's done in MKV extraction.

Signed-off-by: glass <glass@dolby.com>

Author: g-lass

library/common/src/main/java/com/google/android/exoplayer2/audio/MlpUtil.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.audio;
+
+import androidx.annotation.Nullable;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.drm.DrmInitData;
+import com.google.android.exoplayer2.util.MimeTypes;
+import com.google.android.exoplayer2.util.ParsableBitArray;
+import com.google.android.exoplayer2.util.ParsableByteArray;
+import java.nio.ByteBuffer;
+
+/** Utility methods for parsing MLP frames, which are access units in MLP bitstreams. */
+public final class MlpUtil {
+
+  /** The channel count of MLP stream. */
+  // TODO: Parse MLP stream channel count.
+  private static final int CHANNEL_COUNT_2 = 2;
+
+
+  /**
+   * Returns the MLP format given {@code data} containing the MLPSpecificBox according to
+   * dolbytruehdbitstreamswithintheisobasemediafileformat.pdf
+   * The reading position of {@code data} will be modified.
+   *
+   * @param data The MLPSpecificBox to parse.
+   * @param trackId The track identifier to set on the format.
+   * @param sampleRate The sample rate to be included in the format.
+   * @param language The language to set on the format.
+   * @param drmInitData {@link DrmInitData} to be included in the format.
+   * @return The MLP format parsed from data in the header.
+   */
+  public static Format parseMlpFormat(
+      ParsableByteArray data, String trackId, int sampleRate,
+      String language, @Nullable DrmInitData drmInitData) {
+
+    return new Format.Builder()
+        .setId(trackId)
+        .setSampleMimeType(MimeTypes.AUDIO_TRUEHD)
+        .setChannelCount(CHANNEL_COUNT_2)
+        .setSampleRate(sampleRate)
+        .setDrmInitData(drmInitData)
+        .setLanguage(language)
+        .build();
+  }
+
+  private MlpUtil() {}
+}

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java

@@ -152,6 +152,12 @@
   @SuppressWarnings("ConstantCaseForConstants")
   public static final int TYPE_dac4 = 0x64616334;
 
+  @SuppressWarnings("ConstantCaseForConstants")
+  public static final int TYPE_mlpa = 0x6d6c7061;
+
+  @SuppressWarnings("ConstantCaseForConstants")
+  public static final int TYPE_dmlp = 0x646d6c70;
+
   @SuppressWarnings("ConstantCaseForConstants")
   public static final int TYPE_dtsc = 0x64747363;
 

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -28,6 +28,7 @@
 import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.audio.Ac3Util;
 import com.google.android.exoplayer2.audio.Ac4Util;
+import com.google.android.exoplayer2.audio.MlpUtil;
 import com.google.android.exoplayer2.audio.OpusUtil;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.extractor.ExtractorUtil;
@@ -962,6 +963,7 @@ private static StsdData parseStsd(
           || childAtomType == Atom.TYPE_ac_3
           || childAtomType == Atom.TYPE_ec_3
           || childAtomType == Atom.TYPE_ac_4
+          || childAtomType == Atom.TYPE_mlpa
           || childAtomType == Atom.TYPE_dtsc
           || childAtomType == Atom.TYPE_dtse
           || childAtomType == Atom.TYPE_dtsh
@@ -1312,14 +1314,20 @@ private static void parseAudioSampleEntry(
       parent.skipBytes(8);
     }
 
-    int channelCount;
-    int sampleRate;
+    int  channelCount;
+    int  sampleRate;
+    int  sampleRate32 = 0;
     @C.PcmEncoding int pcmEncoding = Format.NO_VALUE;
     @Nullable String codecs = null;
 
     if (quickTimeSoundDescriptionVersion == 0 || quickTimeSoundDescriptionVersion == 1) {
       channelCount = parent.readUnsignedShort();
-      parent.skipBytes(6); // sampleSize, compressionId, packetSize.
+      parent.skipBytes(6);  // sampleSize, compressionId, packetSize.
+
+      int pos = parent.getPosition();
+      sampleRate32 = (int) parent.readUnsignedInt();
+
+      parent.setPosition(pos);
       sampleRate = parent.readUnsignedFixedPoint1616();
 
       if (quickTimeSoundDescriptionVersion == 1) {
@@ -1401,6 +1409,8 @@ private static void parseAudioSampleEntry(
       mimeType = MimeTypes.AUDIO_OPUS;
     } else if (atomType == Atom.TYPE_fLaC) {
       mimeType = MimeTypes.AUDIO_FLAC;
+    } else if (atomType == Atom.TYPE_mlpa) {
+      mimeType = MimeTypes.AUDIO_TRUEHD;
     }
 
     @Nullable List<byte[]> initializationData = null;
@@ -1442,6 +1452,10 @@ private static void parseAudioSampleEntry(
             initializationData = ImmutableList.of(initializationDataBytes);
           }
         }
+      } else if (childAtomType == Atom.TYPE_dmlp) {
+        parent.setPosition(Atom.HEADER_SIZE + childPosition);
+        out.format = MlpUtil.parseMlpFormat(parent, Integer.toString(trackId),
+            sampleRate32, language, drmInitData);
       } else if (childAtomType == Atom.TYPE_dac3) {
         parent.setPosition(Atom.HEADER_SIZE + childPosition);
         out.format =

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.extractor.mp4;
 
+import static com.google.android.exoplayer2.audio.Ac3Util.TRUEHD_RECHUNK_SAMPLE_COUNT;
 import static com.google.android.exoplayer2.extractor.mp4.AtomParsers.parseTraks;
 import static com.google.android.exoplayer2.extractor.mp4.Sniffer.BRAND_HEIC;
 import static com.google.android.exoplayer2.extractor.mp4.Sniffer.BRAND_QUICKTIME;
@@ -44,6 +45,7 @@
 import com.google.android.exoplayer2.metadata.mp4.MotionPhotoMetadata;
 import com.google.android.exoplayer2.metadata.mp4.SlowMotionData;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.Log;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.NalUnitUtil;
 import com.google.android.exoplayer2.util.ParsableByteArray;
@@ -155,6 +157,7 @@ public final class Mp4Extractor implements Extractor, SeekMap {
   private int sampleBytesRead;
   private int sampleBytesWritten;
   private int sampleCurrentNalBytesRemaining;
+  private int lastReadSampleSize;
 
   // Extractor outputs.
   private @MonotonicNonNull ExtractorOutput extractorOutput;
@@ -506,6 +509,12 @@ private void processMoovAtom(ContainerAtom moov) throws ParserException {
       // Each sample has up to three bytes of overhead for the start code that replaces its length.
       // Allow ten source samples per output sample, like the platform extractor.
       int maxInputSize = trackSampleTable.maximumSize + 3 * 10;
+
+      if (track.format.sampleMimeType.equals(MimeTypes.AUDIO_TRUEHD)) {
+        // TrueHD collates 16 source samples per output
+        maxInputSize = trackSampleTable.maximumSize * TRUEHD_RECHUNK_SAMPLE_COUNT;
+      }
+
       Format.Builder formatBuilder = track.format.buildUpon();
       formatBuilder.setMaxInputSize(maxInputSize);
       if (track.type == C.TRACK_TYPE_VIDEO
@@ -554,7 +563,7 @@ private void processMoovAtom(ContainerAtom moov) throws ParserException {
    * @return One of the {@code RESULT_*} flags in {@link Extractor}.
    * @throws IOException If an error occurs reading from the input.
    */
-  private int readSample(ExtractorInput input, PositionHolder positionHolder) throws IOException {
+  private int readSample1(ExtractorInput input, PositionHolder positionHolder) throws IOException {
     long inputPosition = input.getPosition();
     if (sampleTrackIndex == C.INDEX_UNSET) {
       sampleTrackIndex = getTrackIndexOfNextReadSample(inputPosition);
@@ -632,20 +641,75 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder) thro
         sampleCurrentNalBytesRemaining -= writtenBytes;
       }
     }
-    trackOutput.sampleMetadata(
-        track.sampleTable.timestampsUs[sampleIndex],
-        track.sampleTable.flags[sampleIndex],
-        sampleSize,
-        0,
-        null);
+
     track.sampleIndex++;
     sampleTrackIndex = C.INDEX_UNSET;
     sampleBytesRead = 0;
     sampleBytesWritten = 0;
     sampleCurrentNalBytesRemaining = 0;
+    lastReadSampleSize = sampleSize;
     return RESULT_CONTINUE;
   }
 
+  /**
+   * Attempts to extract the next sample or the next 16 samples in case of Dolby TrueHD audio
+   * in the current mdat atom for the specified track.
+   *
+   * <p>Returns {@link #RESULT_SEEK} if the source should be reloaded from the position in {@code
+   * positionHolder}.
+   *
+   * <p>Returns {@link #RESULT_END_OF_INPUT} if no samples are left. Otherwise, returns {@link
+   * #RESULT_CONTINUE}.
+   *
+   * @param input The {@link ExtractorInput} from which to read data.
+   * @param positionHolder If {@link #RESULT_SEEK} is returned, this holder is updated to hold the
+   *     position of the required data.
+   * @return One of the {@code RESULT_*} flags in {@link Extractor}.
+   * @throws IOException If an error occurs reading from the input.
+   */
+  private int readSample(ExtractorInput input, PositionHolder positionHolder) throws IOException {
+    long inputPosition = input.getPosition();
+    if (sampleTrackIndex == C.INDEX_UNSET) {
+      sampleTrackIndex = getTrackIndexOfNextReadSample(inputPosition);
+      if (sampleTrackIndex == C.INDEX_UNSET) {
+        return RESULT_END_OF_INPUT;
+      }
+    }
+
+    Mp4Track track = castNonNull(tracks)[sampleTrackIndex];
+    TrackOutput trackOutput = track.trackOutput;
+    int sampleIndex = track.sampleIndex;
+    int result = readSample1(input, positionHolder);
+
+    if (result != RESULT_CONTINUE) {
+      return result;
+    }
+
+    int sampleSize = lastReadSampleSize;
+
+    if (MimeTypes.AUDIO_TRUEHD.equals(track.track.format.sampleMimeType)) {
+      int untilIdx = sampleIndex + TRUEHD_RECHUNK_SAMPLE_COUNT;
+      int lastIdx = track.sampleTable.sizes.length;
+
+      untilIdx = min(untilIdx, lastIdx);
+
+      while (result == RESULT_CONTINUE && track.sampleIndex < untilIdx) {
+        int i = track.sampleIndex;
+        result = readSample1(input, positionHolder);
+        sampleSize += result == RESULT_CONTINUE ? lastReadSampleSize : 0;
+      }
+    }
+
+    trackOutput.sampleMetadata(
+        track.sampleTable.timestampsUs[sampleIndex],
+        track.sampleTable.flags[sampleIndex],
+        sampleSize,
+        0,
+        null);
+
+    return result;
+  }
+
   /**
    * Returns the index of the track that contains the next sample to be read, or {@link
    * C#INDEX_UNSET} if no samples remain.